@article{GDZPPN002074400, title = {Ungel\"oste Probleme.}, journal = {Elemente der Mathematik}, volume = {14}, year = {1959}, pages = {13-14}, url = {http://dml.mathdoc.fr/item/GDZPPN002074400} }
Hadwiger, H. Ungelöste Probleme.. Elemente der Mathematik, Tome 14 (1959) pp. 13-14. http://gdmltest.u-ga.fr/item/GDZPPN002074400/